Sienna Miller opens up about her pregnancy in April issue of British Vogue magazine

'I'm so excited!' Sienna Miller opens up about her pregnancy as she shows off her curves in a chic new shoot

She's done her best to keep her pregnancy under wraps.

But now Sienna Miller has opened up about expecting her first child with boyfriend Tom Sturridge, and says she is 'very excited' about starting a family.

The 30-year-old star gave the interview as she posed for a chic new shoot in the April issue of British Vogue magazine.

'I'm so excited!' Sienna Miller has opened up about her pregnancy as she poses for a summery new shoot for British Vogue magazinea

Sienna is seen wearing a plunging pale pink gown while holding up a wreath of flowers which spell her name in the summery photographs taken by Ryan McGinley.

The full interview appears in the April issue of British Vogue

She told the publication of her pregnancy: 'I'm feeling fine. It's all progressing nicely and it's very exciting. It's nice to start a new decade.'

However, Sienna added that while she is looking forward to welcoming her first child into the world, she doesn't want to talk too much about the pregnancy because she wants to keep her life as private as possible.

She added: 'I'm in my second trimester, so I'm I-can-talk-about-it pregnant, even though I'm under strict instructions not to say anything as it would completely defeat the point of everything I've tried to achieve in the last eight years.'

The G.I. Joe: Rise of Cobra actress also spoke to the magazine about turning 30, adding that she didn't react to the landmark birthday as she thought she would.

She said: 'I didn’t have the freak-out which I thought I would have. But maybe it’s because I’m the youngest of all my friends – so that lessened the blow. It’s nice to start a new decade.'

Sienna and Tom, most famous for his role in The Boat That Rocked, began dating in mid 2011 shortly after her split from fianc Jude Law.

It is now believed that Sienna and Tom are engaged, although the actress has yet to comment on the rumours.

For the full interview with Sienna, pick up the April issue of British Vogue magazine, out on March 12th. For more, visit Vogue.co.uk.

Expanding their family: The baby will be the first for Sienna and rumoured fianc Tom Sturridge